Circuit breaker operating mechanism



March 2, 1965 w. H. wooos 3,171,921

CIRCUIT BREAKER OPERATING MECHANISM Filed Oct. 3, 1960 a'sneets-sneet 1 INVEN TOR.

W/LL IAM H. WOODS March 2, 1965 V w. H. WOODS 3,171,921

' cmcun" BREAKER OPERATING MECHANISM Filed Oct. 3, 1960 3 Sheets-Sheet 2 INVENTOR.

W/LL/AM H WO S March 2, 1965 w. 1-1. wooos CIRCUIT BREAKER OPERATING MECHANISM 3 Sheets-Sheet 3 Filed Oct. 3, 1960 GIMP/V INVENTOR.

W/LL 64M *1. WOODS 741% United States Patent 3,171,921 ClltCEJll BREAKERGPERAHNG MECHANlSll fi William H. Woods, Cedar Rapids, lowa, assignor to Square 1) Company, Parlr'llidge, ill, a corporation of Michigan Filed (Dot. 3, 1962), Ser. No. @llgllilll 3 Claims. {(1 Millild} This invention relates generally to electrical circuit breakers and, particularly, to operating mechanisms therefor.

Patent No. 2,902,560 for Circuit Breaker, issued Sep tember l, 1959t0 Stanbaclc et al. and assigned to the same assignee as the present invention, discloses ja molded case circuit breaker employing'a toggle operated 'overcenter spring mechanism. This type of mechanism, which is in widespread use and performs satisfactorily, comprises a movable contact carrier having one end pivoted against a movable manual operator and a'tension spring having one end attachednear the other end of the contact carrier. The other end of the tension spring is attached to a movable cradle member which is maintained in latched position by a suitable electroresponsive tripping mechanism. During tripping it is 'first necessary for the cradle member to move to carry the tension spring over center before the movable contact carrier can move to contact-open position. Thus, there is a time delay anda period of decreasing contact pressure, bothundesirable, before the contacts open. Furthermore, use of the same strong tension spring to :holdthecontacts closed and jto force cradle member, against the trihpingmechanism results in undue force being exerted on the latter, such force tending to interfere "with proper calibration of the tripping mechanism. It :is desirable, therefore, *to provide'an improved type of toggle operated overcenter spring mechanism for circuit "breakers whichovercomes the aforesaid disadvantages andihas additional advantages.

Accordingly,it is an object of this inventionto provide ah improved circuit breakermechahism wherein manual opening and closure of its contacts is carried 'out by moving an overcenter'spring overc'enter'and wherein automatic opening of its contacts during tripping is initiated by movementof its movable contact toward contact-open position before the overcenter spring'pa'sses over center.

Another'object is to provide a circuit breaker mechanism of the aforesaid character wherein contact'opening during tripping is'initiated by a direct blow on its movable contact carrier.

Another obiect f to provide a circuit breaker mecl anism of the aforesaid character wherein the overceriter spring is distinct from biasing means which ini'tiate contact opening during tripping.

Another object is to provide improved meansfor mounting the rnovablecontact carrier of the circuit breaker mechanism.

Another object is to provide improved means for mounting the overcenter spring.

Amore specific object isto provide an improved circuit breaker mechanism wherein thernov'abie contact carrier is pivotally mounted on a pivotable operating member and a compression type overcenter spring is disposed between the contact carrier and the operating member and wherein a movable cradle member having its own biasing spring in adapted to be latched in untripped position by an electro'responsive trip mechanism and is adapted to be unlatched for movement toward tripped position during which itacts directlyupon the contact carrier LO effect contact separation before the overcenter spring passes over center.

Other objects and advantages of the invention will hereina fter appear.

3,l?l,92l Patented Mar. 2, 1965 ice The accompanying drawings illustrate a preferred embodiment of the invention, it being understood that the embodiment illustratedis susceptible of modification with respect to details thereof without departing from the scope of the appended claims.

In the drawings: I

"FIG. 1 is a side view of a circuit breaker incorporating 'the'invention with its side coverremoved and showingthe circuit breaker mechanism disposed in on or closed position.

FIG. 2 is similar to FIG. l but shows the circuit breaker mechanism disposed'in off or open.position.

FIG. 3 is similar to FlGS. 1 and '2 but shows .theciricuit breaker mechanism disposed .in tripped position.

.FlG. 4 is a cross sectional viewof the circuit breaker along the line 4 l of FIG. 3,

With reference to the drawings, the circuit breaker in which the present invention isjembodied comprises a case 1%) which is formed by an open-sided base member 11 :and a cover member 12 therefor which is secured thereto by a plurality of rivets "13. The base li and cover 1?; are preferably molded from suitable electrical insulating material and are provided with complementary recesses and projections which afford support for the circuit breaker mechanism, hereinafter described. The case 19 is provided with suitable openings through which extend the manual operatin'g member and the electrical connecting members for the circuit breaker mechanism.

A manual operating member 14 having a'handle portion extending outwardly of the case '16 through the top wall thereof and having a bodyportionprovided with a pair of legs ldextending inwardly into the case is provided with trunnions 16 which are journalled in suitable b'earingrecesses 17 (see FIG. '4) in the case to pivotally support the manual operating member.

Apin 18 extends between'and issupported bythe legs 15 of the manualoperating member 14 and a spring guide'link l9, hereinafter-described, ispivotally supported on the pin and depends therefrom.

A movable contact carrier member 2tl'havinga pair of upwardly extending legs 2-1, each of which is provided witha circular aperture-22 near its uppermost end, is pivotally supported on thetrunnions 1d of'the manual operating-member M conceivably, the movable'contact carrier 2d could be pivoted directly on the case ltlinstead of on the tru'nnions 16 of the manual opcratin member 14 if suitable provisions were made therefor. The movable contact carrier *Zll is 'movable clockwise to contact-closed position and .is movable in the opposite direction to contact-open position; travel in the latter direction being limited by a stop projection 23 molded in the case it as FIGS. 2 and 3 show. The stop projection '23 also serves to limit clockwisetravel of a movable cradle member 24, hereinafter described, as H6. 3 shows.

The legs 21 of the movable contact carrier-2t) rigidly support a guide pin 25 therebetween which serves as a bearing surface for the lower end of an overcenter spring 26 which is of the compression type. The upperend .of the overcenter spring 25 is intended toexert a force onthe manual operator id but it is notpractical in the embodiment shown to "have the upper end of the; overcenter spring -26 bear directly thereagainst. Accordingly, the spring guide link 19 is provided and the oyercenter spring 26 surrounding it bears against the shoulders 27 provided near the upper end of the spring guide link. The spring guidelinlr l9 insures that the overc'enter spring 26 is properly disposed With'respect to the'manual operator memberltd'and the movable contact carrier 20 no matter what relative po'sitionthey"assume. Thefspring guide linlr i9 is provided with anaperture or slot 28 which slidingly accommodates the guide pin 25 on the movable contact carrier 2t).

The lower end of the movable contact carrier 2G is provided with a movable contact 29 which is electrically and mechanically connected thereto and is adapted to cooperate with a stationary contact 30 which is electrically and mechanically connected to an electrically conductive spring jaw clip 31. The spring jaw clip 31 is supported on the case by entrapment and adapts the circuit breaker for electrical connection to an electrical terminal (not shown) on a circuit breaker panelboard (not shown).

The U-shaped cradle or tripping member 24 is pivotally supported at one end on a hub 32 formed on the base 11 of the case 10. The cradle 24 extends between the legs 15 of the manual operator 14 above the pin 18 carried by the latter. The cradle 24 is biased for retation in the clockwise direction (with respect to FIGS. 1, 2 and 3) about the hub 32 by a biasing spring 33 which is disposed between the left end wall of the case 10 and the cradle. It is preferred that the biasing spring 33 be of the compression type and that it be of conical configuration so that nesting or telescoping of the convolutions thereof occurs during compression in order to conserve space. The biasing spring 33 must be sufliciently strong to overcome the force of the overcenter spring 26 when the latter is acting to maintain the movable contact carrier in closed position, as will hereinafter appear. The cradle 24 is provided with a projection 34 which cooperates with one end of the biasing spring 33 to maintain the latter in proper position. The cradle 24 is further provided with a transversely disposed reset pin 35 which is adapted to cooperate with the legs 21 of the movable contact carrier 20 when tripping occurs and with the legs 15 of the manual operator 14 when the circuit breaker mechanism is being reset, as will hereinafter appear. The cradle 24 is provided at its other end with a latching portion 36 which is adapted to cooperate with a current responsive tripping mechanism 37.

The electroresponsive tripping mechanism 37, which is adapted to latch the cradle 24 in one position and to release it for movement to another position during tripping, is supported by an electrically conductive terminal strap 38 which is supported by the case 10 and is provided with a terminal screw 39 at its exterior end portion. The strap 38 is provided with a calibration screw 40 which is rotatable to move the strap 33 thereby chang ing the position of the tripping mechanism 37. As will be understood, the particular construction of the current responsive tripping mechanism 37, hereinafter briefly described, forms no part of the present invention and equivalent tripping mechanisms may be employed. However, reference may be had to Patent No. 2,902,560, hereinbefore referred to, for a more complete description of the construction and operation of a current responsive tripping mechanism substantially identical to that disclosed herein. The current responsive tripping mechanism 37 comprises an electrically conductive bimetallic member 41 which is welded at its upper end portion to the terminal strap 38. One end of a flexible electrical conductor 42 is electrically connected to the bimetallic member 41 and the other end is electrically connected to the movable contact carrier 20. A magnetic yoke member 43 is welded to the lower or free end portion of the bimetallic member 41. A movable magnetic armature member 44 is pivotally supported on the yoke 43 and is biased thereagainst by a helical compression spring 45 which is disposed between the top wall of the case 10 and the armature. The armature member 44 is provided with an aperture 46 in which a hardened steel member 47 is secured and the member 47 aifords a latch surface 48 for the latching portion 36 of the cradle 24. A U-shaped ambient tempera ture compensation bimetallic member 49 has one end rigidly attached to the lower end portion of the yoke 43 and the other end of the member 49 bears against the free end of the armature 44 to maintain the latter in predetermined position.

The circuit breaker operates in the following manner.

With reference to FIG. 2, the circuit breaker mechanism is shown in manually opened condition wherein the overcenter spring as is disposed over center in the left-hand direction thereby causing the manual operator 14- to be biased to its extreme position in the clockwise direction and causing the movable contact carrier 20 to be biased to its extreme position in the counterclockwise direction against the stop projection 23. The cradle 24 is latched in untripped position by the tripping mechanism 37 and the biasing spring 33 therefor is compressed.

The circuit breaker mechanism is moved from the manually opened condition shown in FIG. 2 to the closed condition shown in FIG. 1 by manually moving the manual operator 14 to its extreme position in the counterclockwise direction thereby causing the overcenter spring 26 to be carried over center in the right-hand direction. The overcenter spring 26 acts upon the guide pin 25 to bias the movable contact carrier member 20 in the clockwise direction whereupon contact is established between the movable contact 29 and the stationary contact 30. Thus, an electrical circuit is completed from the spring jaw clip 31, through the stationary contact 30, the movable contact 29, the movable contact carrier 20, the flexible conductor 42, the bimetallic member 41 of the tripping mechanism, 37, to the electrically conductive strip 38. The cradle 24 remains latched in untripped position by the tripping mechanism 37 and the biasing spring 33 therefor remains compressed.

The circuit breaker mechanism is moved from the closet condition shown in FIG. 1 to the tripped open condition shown in FIG. 3 in response to an abnormal circuit condition which causes movement of the latch surface 48 on the tripping mechanism 37 away from the eradle 24. When this occurs, the latch surface 48 of the tripping mechanism 37 becomes disengaged from the latching portion 36 of the cradle 24 and the cradle, under the action of the biasing spring 33 which tends to decompress, rotates in the clockwise direction to its eX'- treme position against the stop projection 23. As the cradle 24 rotates, the reset pin 35 carried thereby strikes directly against the legs 21 of the movable contact carrier 20 causing the latter to move in the counterclockwise direction thereby eifecting separation of the movable contact 29 and the stationary contact 30. As the contact carrier member 20 moves, it carries the overcenter spring 26 over center in the left-hand direction and the overcenter spring then biases the movable contact carrier 20 against the stop projection 23 and biases the manual operator 14 from its extreme leftward position to a central or upright position. Movement of the manual operator 14 to its extreme rightward position is prevented because the legs 15 of the manual operator memher come to rest against the reset pin 35 on the cradle 24, as FIG. 3 shows.

The circuit breaker mechanism is reset, that is to say, moved from the tripped open condition to the open condition shown in FIG. 2, by manually moving the manual operator 14 in the clockwise direction so that the legs 15 thereof bear against the reset pin 35 on the cradle 24- to cause the latter to rotate in a counterclockwise direction against the biasing spring 33 until the latching portion 36 of the cradle 24 re-engages the latch surface 48 of the tripping mechanism 37. The circuit breaker mechanism then assumes the open condition shown in FIG. 2 and is in readiness to be moved to the closed condition shown in FIG. 1.

What is claimed is:

1. An electric circuit breaker comprising an insulating case, manually operable means pivotable on said case about a point, contact carrying means pivotable to circuit open and circuit closed positions, spring guide means pivotally supported on said manually operable means and slidabl'y associated with said contact carrying means, compression type overcenter spring means supported by said spring guide means and adapted to bias said contact carrying means and said manually operabe means in opposite rotative directions, the line of action of said overcenter spring means being shiftable by said manually operable means to cause actuation of said contact carrying means, tripping means pivotable on said case and movable to latched and unlatched positions, biasing means disposed between said tripping means and said case to bias said tripping means toward unlatched position, and electroresponsive means supported by said case normally maintaining said tripping means in latched position and being operable to permit movement of said tripping means to unlatched position, said tripping means being adapted to move said contact carrying means toward circuit open position and effect shifting of the line of action of said overcenter spring means across said point by said contact carrying means.

2. An electric circuit breaker comprising an insulating case having a pair of confronting walls, a bearing recess in each of said confronting walls, a manually operable member having trunnions which are journalled in said bearing recesses for pivoting about a point, said manually operable member also having a handle exterior of sai case and a bifurcated portion within said case, first support means mounted between the two legs of said bifurcated portion of said manually operable member, a spring guide pivotally supported on said first support means and having a slot therein, a movable contact carrying member having a pair of legs, each of said legs being provided with an aperture which adapts the movable contact carrying member to be pivotally supported on the trunnions of said manually operable member for movement to circuit open and circuit closed positions, second support means mounted between the two legs of said movable contact carrying member, said second support means being adapted for sliding engagement with said slot in said spring guide, a helical compression spring surrounding said spring guide for actuating said contact carrying member and for biasing the latter and said manually operable member in opposite rotative directions, one end of said spring bearing against said second support means and the other end of said spring bearing against a shoulder provided on said spring guide, tripping means pivotable on said case and movable to latched and unlatched positions, said tripping means extending between the two legs of said bifurcated portion of said manually operable member inwardly of said first support means, biasing means disposed between said tripping means and said case to bias said tripping means toward unlatched position, and electroresponsive means supported by said case normally maintaining said tripping means in latched position and being operable to permit movement of said tripping means to unlatched position, said tripping means being adapted to move said contact carrying means toward circuit open position and effect shifting of the line of action of said overcenter spring means across said point by said contact carrying means.

3. An electric circuit breaker comprising an insulating support, a manually operable member pivotable on said support about a point, said manually operable member having a handle portion and a leg portion, a movable contact carrying member pivotable on said manually operable member about said point to circuit open and circuit closed positions, said movable contact carrying member also carrying a pin, a guide link having one end pivotally mounted on said leg portion of said manually operable member and having its other end slidably associated with said pin on said movable contact carrying member, a helical compression spring surrounding said guide link and having one end bearing against said pin and having its other end bearing against a portion of said guide link, said compression spring being adapted to be moved over center by said manually operable member to cause actuation of said contact carrying member, said compression spring being further adapted to bias said manually operable member and said movable contact carrying member in opposite rotative directions, a tripping member pivotable on said support and movable to latched and unlatched positions, electroresponsive means normally maintaining said tripping member in latched position and being operable to permit movement of said tripping member toward unlatched position, and biasing means disposed between said support and said tripping member to move the latter toward its unlatched position, said tripping member having a portion adapted to strike said movable contact carrying member to initiate movement of the latter toward circuit open position, and said tripping member portion being further adapted to be engaged by said leg portion of said manually operable member as the latter is moved to reset said tripping member after the latter has moved to unlatched position.

References Cited in the file of this patent UNITED STATES PATENTS 1,726,233 Krantz Aug. 27, 1929 2,174,232 Baker Sept. 26, 1939 2,214,695 Jennings Sept. 10, 1940 2,334,007 Hutt Nov. 9, 1943 2,416,170 Gano et al Feb. 8, 1947 2,443,090 Wise June 8, 1948 2,467,797 Wise Apr. 19, 1949 2,473,848 Baxter June 21, 1949 2,504,793 Baxter Apr. 18, 1950 2,688,057 Slater Aug. 31, 1954 2,693,516 Drobney et a1 Nov. 2, 1954 2,797,278 Gelzheiser et al. June 25, 1957 2,889,428 Kingdom et a1. June 2, 1959 3,061,698 Lyon Oct. 30, 1962 FOREIGN PATENTS 621,416 Great Britain Apr. 8, 1949 11,552 Great Britain June 2, 1899 

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING AN INSULATING CASE, MANUALLY OPERABLE MEANS PIVOTABLE ON SAID CASE ABOUT A POINT, CONTACT CARRYING MEANS PIVOTABLE TO CIRCUIT OPEN AND CIRCUIT CLOSED POSITIONS, SPRING GUIDE MEANS PIVOTALLY SUPPORTED ON SAID MANUALLY OPERABLE MEANS AND SLIDABLY ASSOCIATED WITH SAID CONTACT CARRYING MEANS, COMPRESSION TYPE OVERCENTER SPRING MEANS SUPPORTED BY SAID SPRING GUIDE MEANS AND ADAPTED TO BIAS SAID CONTACT CARRYING MEANS AND SAID MANUALLY OPERABLE MEANS IN OPPOSITE ROTATIVE DIRECTIONS, THE LINE OF ACTION OF SAID OVERCENTER SPRING MEANS BEING SHIFTABLE BY SAID MANUALLY OPERABLE MEANS TO CAUSE ACTUATION OF SAID CONTACT CARRYING MEANS, TRIPPING MEANS PIVOTABLE ON SAID CASE AND MOVABLE TO LATCHED AND UNLATCHED POSITIONS, BIASING MEANS DISPOSED BETWEEN SAID TRIPPING MEANS AND SAID CASE TO BIAS SAID TRIPPING MEANS TOWARD UNLATCHED POSITION, AND ELECTRORESPONSIVE MEANS SUPPORTED BY SAID CASE NORMALLY MAINTAINING SAID TRIPPING MEANS IN LATCHED POSITION AND BEING OPERABLE TO PERMIT MOVEMENT OF SAID TRIPPING MEANS TO UNLATCHED POSITION, SAID TRIPPING MEANS BEING ADAPTED TO MOVE SAID CONTACT CARRYING MEANS TOWARD CIRCUIT OPEN POSITION AND EFFECT SHIFTING OF THE LINE OF ACTION OF SAID OVERCENTER SPRING MEANS ACROSS SAID POINT BY SAID CONTACT CARRYING MEANS. 